1. Field of the Invention
The present invention relates to an analytical cell suitable for use, for example, in performing an electrode reaction analysis in relation to analytical equipment.
2. Description of the Related Art
As is well known, in an electric cell, a negative electrode active material and a positive electrode active material undergo electrode reactions in a charge-discharge process. In recent years, such electrode reactions have been analyzed during the charge-discharge process using analytical equipment. For example, an analytical cell, which can be observed by a transmission electron microscope (TEM), has been proposed in In-situ Electron Microscopy of Electrical Energy Storage Materials [online], 2014, retrieved from the Internet on Jan. 30, 2014 <URL: http://www1.eere.energy.gov/vehiclesandfuels/pdfs/merit_review_2011/electrochemical_storage/es095_unocic_2011_o.pdf>.
Such an analytical cell contains a pair of silicon substrates, each of which includes a rectangular observation window having a size of about 50 μm×100 μm. The silicon substrates are stacked at a predetermined distance from each other to form an overlapping portion, in such a manner that the observation windows face toward each other. A negative electrode active material containing highly oriented graphite, and a positive electrode active material containing LiCoO2 are deposited on one of the silicon substrates by an ion beam deposition method, so that the negative electrode active material and the positive electrode active material are located between the observation windows. Incidentally, the negative electrode active material and the positive electrode active material are each extracted from a bulk body using a focused ion beam (FIB).
The negative electrode active material and the positive electrode active material (hereinafter also referred to simply as active materials) are connected electrically to a negative electrode collector and a positive electrode collector (hereinafter also referred to simply as collectors), respectively, in the overlapping portion. The collectors extend respectively from inside of the overlapping portion and are exposed to the outside. Therefore, the active materials can be connected electrically to the exterior of the overlapping portion by the collectors.
Electrode reactions and the like of the active materials can be analyzed by observing the analytical cell using the transmission electron microscope (TEM). More specifically, at first, the analytical cell is placed in one end of a TEM holder having a passage for introduction of an electrolytic solution to the overlapping portion. Then, the electrolytic solution is introduced from the passage of the TEM holder into the overlapping portion, and the collectors are each connected to a charge-discharge tester or the like, whereby the active materials undergo electrode reactions. TEM observation is carried out while transmitting an electron beam through the observation window in order to analyze the electrode reactions of the active materials.